This paper describes how to carry out environmental impact assessment in an envi-ronmentally sensitive zone. The principles, the train of thought and methods are proposed in this paper. We have made the water environm...This paper describes how to carry out environmental impact assessment in an envi-ronmentally sensitive zone. The principles, the train of thought and methods are proposed in this paper. We have made the water environmental impact assessment on the engineering pro-ject of technical reform in Guiyang Battery Mill. The basis for engineering construction and environmental protection in this mill has been laid dawn.展开更多
The development of the national economy is closely tied to infrastructure construction.In recent years,China has seen a significant increase in the number and scale of road construction projects,aimed at facilitating ...The development of the national economy is closely tied to infrastructure construction.In recent years,China has seen a significant increase in the number and scale of road construction projects,aimed at facilitating the flow of goods and enabling convenient travel for the masses.However,this surge in road construction also raises concerns about road traffic safety.Road traffic safety facilities play a crucial role in warning and protecting against traffic accidents.To ensure their effective implementation,this paper analyzes the essence of road traffic facilities and their impact on traffic safety.By identifying challenges in the application of traffic safety facilities and adhering to safety facility application principles,suggestions are proposed to enhance traffic safety management.展开更多
The paper presents the theory of Hamilton variation principle which is the current method for impact problem, central difference method which is efficient solution of finite element (FE) method for impact problem and ...The paper presents the theory of Hamilton variation principle which is the current method for impact problem, central difference method which is efficient solution of finite element (FE) method for impact problem and adapts to solve non-linear dynamic problem. And it introduces the ANSYS/LS-DYNA which is the popular FE software for impact problem both at home and abroad. Then it gives solutions for one simple model by analytical method and ANSYS/LS-DYNA respec-tively to validate function of software, and they are consistent. Afterward, it gives model of single-layer Kiewitt reticulated dome with a span of 60 m, and the cylinder impactor, and introduces the contact interface arithmetic, especially the material model of steel (piecewise linear plasticity model) which takes stain rate into account and makes steel failure stress higher under impact loads. The vertical displacement, stress in main members, and the plastic deformation for dome under impact loads were obtained. Then four failure modes (no failure, moderate failure, global failure and slight failure) were summarized according to the rules of dynamic response. And the characteristics of dynamic response for each failure mode were shown.展开更多
The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one...The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one of the main difficulties in many engineering applications. The numerical approaches being used widely in impact analysis are mainly from two fields： multibody system dynamics （MBS） and computational solid mechanics （CSM）. Approaches based on MBS provide a more efficient yet less accurate analysis of the contact/impact problems, while approaches based on CSM are well suited for particularly high accuracy needs, yet require very high computational effort. To bridge the gap between accuracy and efficiency in the dynamic simulation of a flexible multibody system with contacts/impacts, a partition method is presented considering that the contact body is divided into two parts, an impact region and a non-impact region. The impact region is modeled using the finite element method to guarantee the local accuracy, while the non-impact region is modeled using the modal reduction approach to raise the global efficiency. A three-dimensional rod-plate impact experiment is designed and performed to validate the numerical results. The principle for how to partition the contact bodies is proposed： the maximum radius of the impact region can be estimated by an analytical method, and the modal truncation orders of the non-impact region can be estimated by the highest frequency of the signal measured. The simulation results using the presented method are in good agreement with the experimental results. It shows that this method is an effec-rive formulation considering both accuracy and efficiency. Moreover, a more complicated multibody impact problem of a crank slider mechanism is investigated to strengthen this conclusion.展开更多
The normal impact of an elastic initially static beam of finite length on an elastic foundation by a finite elastic rod with initial velocity is investigated in this paper. The approximate formulas for the impact forc...The normal impact of an elastic initially static beam of finite length on an elastic foundation by a finite elastic rod with initial velocity is investigated in this paper. The approximate formulas for the impact force are obtained by the Galerkin principle.Some discussions are made and conclusions are drawn.展开更多
通过准静态力学性能实验和动态热机械实验研究Q411T聚脲材料的基本力学性能和动态热机械性能;基于时温等效原理(TTS)拟合Q411T聚脲的损耗模量、储能模量主曲线,研究Q411T聚脲吸能特性。采用4 kg钢球进行落球冲击试验,通过DH5960动态信...通过准静态力学性能实验和动态热机械实验研究Q411T聚脲材料的基本力学性能和动态热机械性能;基于时温等效原理(TTS)拟合Q411T聚脲的损耗模量、储能模量主曲线,研究Q411T聚脲吸能特性。采用4 kg钢球进行落球冲击试验,通过DH5960动态信号测试分析系统采集钢板在冲击荷载作用下的应变时程曲线,分析有无防护涂层的钢板抗冲击防护效果。结果表明:Q411T型聚脲材料具有良好的力学性能和抗冲击能力,材料的玻璃化转变温度为-20℃,损耗因子的峰值为0.18,在常温状态下材料的损耗因子大于0.12,具有一定的吸能特性;落球冲击试验表明,在钢板迎撞面喷涂2 mm Q411T涂层可以有效抑制结构变形,试样挠度下降45%,钢板抗冲击性能显著提高。展开更多
文摘This paper describes how to carry out environmental impact assessment in an envi-ronmentally sensitive zone. The principles, the train of thought and methods are proposed in this paper. We have made the water environmental impact assessment on the engineering pro-ject of technical reform in Guiyang Battery Mill. The basis for engineering construction and environmental protection in this mill has been laid dawn.
文摘The development of the national economy is closely tied to infrastructure construction.In recent years,China has seen a significant increase in the number and scale of road construction projects,aimed at facilitating the flow of goods and enabling convenient travel for the masses.However,this surge in road construction also raises concerns about road traffic safety.Road traffic safety facilities play a crucial role in warning and protecting against traffic accidents.To ensure their effective implementation,this paper analyzes the essence of road traffic facilities and their impact on traffic safety.By identifying challenges in the application of traffic safety facilities and adhering to safety facility application principles,suggestions are proposed to enhance traffic safety management.
基金Supported by National Natural Science Foundation of China(No.90715034)
文摘The paper presents the theory of Hamilton variation principle which is the current method for impact problem, central difference method which is efficient solution of finite element (FE) method for impact problem and adapts to solve non-linear dynamic problem. And it introduces the ANSYS/LS-DYNA which is the popular FE software for impact problem both at home and abroad. Then it gives solutions for one simple model by analytical method and ANSYS/LS-DYNA respec-tively to validate function of software, and they are consistent. Afterward, it gives model of single-layer Kiewitt reticulated dome with a span of 60 m, and the cylinder impactor, and introduces the contact interface arithmetic, especially the material model of steel (piecewise linear plasticity model) which takes stain rate into account and makes steel failure stress higher under impact loads. The vertical displacement, stress in main members, and the plastic deformation for dome under impact loads were obtained. Then four failure modes (no failure, moderate failure, global failure and slight failure) were summarized according to the rules of dynamic response. And the characteristics of dynamic response for each failure mode were shown.
基金supported by the National Natural Science Foundation of China (Grants 11772188, 11132007)
文摘The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one of the main difficulties in many engineering applications. The numerical approaches being used widely in impact analysis are mainly from two fields： multibody system dynamics （MBS） and computational solid mechanics （CSM）. Approaches based on MBS provide a more efficient yet less accurate analysis of the contact/impact problems, while approaches based on CSM are well suited for particularly high accuracy needs, yet require very high computational effort. To bridge the gap between accuracy and efficiency in the dynamic simulation of a flexible multibody system with contacts/impacts, a partition method is presented considering that the contact body is divided into two parts, an impact region and a non-impact region. The impact region is modeled using the finite element method to guarantee the local accuracy, while the non-impact region is modeled using the modal reduction approach to raise the global efficiency. A three-dimensional rod-plate impact experiment is designed and performed to validate the numerical results. The principle for how to partition the contact bodies is proposed： the maximum radius of the impact region can be estimated by an analytical method, and the modal truncation orders of the non-impact region can be estimated by the highest frequency of the signal measured. The simulation results using the presented method are in good agreement with the experimental results. It shows that this method is an effec-rive formulation considering both accuracy and efficiency. Moreover, a more complicated multibody impact problem of a crank slider mechanism is investigated to strengthen this conclusion.
文摘The normal impact of an elastic initially static beam of finite length on an elastic foundation by a finite elastic rod with initial velocity is investigated in this paper. The approximate formulas for the impact force are obtained by the Galerkin principle.Some discussions are made and conclusions are drawn.
文摘通过准静态力学性能实验和动态热机械实验研究Q411T聚脲材料的基本力学性能和动态热机械性能;基于时温等效原理(TTS)拟合Q411T聚脲的损耗模量、储能模量主曲线,研究Q411T聚脲吸能特性。采用4 kg钢球进行落球冲击试验,通过DH5960动态信号测试分析系统采集钢板在冲击荷载作用下的应变时程曲线,分析有无防护涂层的钢板抗冲击防护效果。结果表明:Q411T型聚脲材料具有良好的力学性能和抗冲击能力,材料的玻璃化转变温度为-20℃,损耗因子的峰值为0.18,在常温状态下材料的损耗因子大于0.12,具有一定的吸能特性;落球冲击试验表明,在钢板迎撞面喷涂2 mm Q411T涂层可以有效抑制结构变形,试样挠度下降45%,钢板抗冲击性能显著提高。
